Rotor and permanent magnet motors

Abstract

This application relates to a rotor and a permanent magnet motor. The rotor includes a rotor core and a plurality of permanent magnets. The rotor core includes a shaft hole, and a plurality of mounting cavities are spaced apart on the outer periphery of the shaft hole. The permanent magnets are embedded in the mounting cavities. Every two adjacent permanent magnets with the same polarity form a V-shaped magnetic pole with the tip of the magnetic pole facing the shaft hole. The area of ​​the permanent magnet is S1, the remanence of the permanent magnet is Br, the outer diameter of the rotor core is R, and the diameter of the shaft hole is r. S1, Br, R, and r satisfy: 0.051 ≤ S1 * Br / (R 2 -r 2 The rotor according to this application can fully utilize the magnetic focusing effect of the magnetic poles, effectively improve the air gap magnetic flux density of the permanent magnet motor, improve the back electromotive force waveform, and help improve the torque output performance of the permanent magnet motor, thereby improving the efficiency of the permanent magnet motor when operating at low frequency, while avoiding magnetic circuit saturation of the rotor core.

Description

Technical Field

[0001] This application relates to the field of motor technology, and more particularly to a rotor and permanent magnet motor. Background Technology

[0002] To increase the reluctance torque ratio, existing permanent magnet synchronous reluctance motors mostly adopt rotors with double or more permanent magnet arrangements and stators with distributed winding structures.

[0003] A double-layer rotor structure generally refers to a double-layer "crescent" structure or a double-layer "U"-shaped structure. The double-layer "crescent" structure uses two tile-shaped permanent magnets per pole. This structure has poor manufacturability, high manufacturing difficulty, and high magnetization requirements. The double-layer "U"-shaped structure uses four or more square permanent magnets per pole. This requires a large number of permanent magnets for rotor manufacturing, has poor manufacturability, and the magnetic circuit between multiple permanent magnets is prone to saturation, hindering further improvement in motor efficiency. Summary of the Invention

[0004] This application provides a rotor to solve the problem of easy saturation of the magnetic circuit between multiple permanent magnets.

[0005] In a first aspect, this application provides a rotor, including a rotor core and a plurality of permanent magnets. The rotor core includes a shaft hole, and a plurality of mounting cavities are spaced apart on the outer periphery of the shaft hole. The permanent magnets are embedded in the mounting cavities. Every two adjacent permanent magnets with the same polarity form a V-shaped magnetic pole with the tips of the magnetic poles facing the shaft hole. The cross-sectional area of ​​the permanent magnet in the radial direction of the rotor core is S1, the remanence of the permanent magnet is Br, the outer diameter of the rotor core is R, and the diameter of the shaft hole is r. S1, Br, R, and r satisfy: 0.051 ≤ S1 * Br / (R 2 -r 2 )≤0.053.

[0006] According to the rotor of this application, every two adjacent permanent magnets with the same polarity form a V-shaped distribution of magnetic poles with the tips of the magnetic poles facing the shaft hole. When this type of rotor is applied to a permanent magnet motor, it makes full use of the magnetic focusing effect of the magnetic poles, which can effectively improve the air gap magnetic flux density of the permanent magnet motor, improve the back electromotive force waveform, and help improve the torque output performance of the permanent magnet motor. The larger the remanence and cross-sectional area of ​​the permanent magnet, the stronger the anti-demagnetization ability of the permanent magnet. However, if the remanence and area are too large, it will affect the mechanical structural strength of the rotor core on the one hand, and may also increase the production cost on the other hand, and cause magnetic circuit saturation. Therefore, the ratio of the product of the remanence and the cross-sectional area of ​​the permanent magnet to the cross-sectional area of ​​the rotor core is set to meet a certain range, so as to improve the efficiency of the permanent magnet motor when operating at low frequency and avoid magnetic circuit saturation of the rotor core.

[0007] According to the rotor of this application, the number of magnetic poles is P, P is greater than or equal to 8, and the included angle of the magnetic poles is θ, θ satisfies: 0 < θ < 50°.

[0008] According to the rotor of this application, more magnetic poles can be arranged within a limited space. When the rotor is applied to a permanent magnet motor, it helps to improve the power density of the permanent magnet motor. When the size of the shaft hole is fixed, the width of the permanent magnet is affected by the angle between the magnetic poles. The smaller θ is, the larger the width of the permanent magnet, which in turn affects the performance parameters of the permanent magnet motor, such as the air gap flux density and cogging torque. Therefore, it is necessary to set an appropriate value for θ to ensure the air gap flux density of the permanent magnet. Thus, this setting can ensure that the permanent magnet can withstand a large operating current without demagnetizing during operation.

[0009] It is understandable that within the range of 0 to 50°, as the included angle increases, the magnetic permeable area inside the rotor core gradually increases, the magnetic reluctance of the magnetic circuit decreases, and the air gap magnetic flux density increases. Therefore, it can be set appropriately according to needs.

[0010] Optionally, the cross-sectional shape of the permanent magnet in the radial direction of the rotor core is rectangular, the width of the permanent magnet is Lm, and the thickness is Hm, where Lm and Hm satisfy: 0.37 <Lm / (R-r)<0.4,5<Lm / Hm<6。

[0011] According to the rotor of this application, the magnetic reluctance of the direct-axis magnetic circuit of the permanent magnet is mainly determined by the thickness of the permanent magnet in the magnetization direction, which will cause changes in the performance of the permanent magnet motor. Within a certain range, increasing the thickness of the permanent magnet will increase the energy of the magnetic field of the permanent magnet, and the air gap magnetic flux density and cogging torque will also increase. At the same time, the magnetic reluctance of the direct-axis magnetic circuit will also increase. However, when it exceeds a certain range, local magnetic flux saturation will occur in the rotor core. Increasing the width of the permanent magnet will reduce the leakage magnetic phenomenon and generate a stronger permanent magnet torque. However, when it exceeds a certain range, local magnetic flux saturation will occur in the rotor core. Therefore, it is necessary to reasonably set the values ​​of Lm and Hm to avoid magnetic flux saturation.

[0012] According to the rotor of this application, the permanent magnet includes a first sub-section and a second sub-section arranged sequentially along the width direction. The first sub-section is close to the shaft hole, and the second sub-section is close to the outer circle of the rotor core. The coercivity of the second sub-section is greater than that of the first sub-section.

[0013] According to the rotor of this application, the magnetic circuit is more dense in the direction closer to the outer circle of the rotor core, making it easier to demagnetize. Setting the coercivity of the second sub-part to be greater than that of the first sub-part can improve the demagnetization resistance of the permanent magnet.

[0014] Optionally, the cross-sectional shape of both the first sub-part and the second sub-part is rectangular, and the width of the first sub-part is greater than the width of the second sub-part.

[0015] According to the rotor of this application, materials with high coercivity are more expensive. Setting the width of the first sub-part to be greater than the width of the second sub-part can effectively reduce the overall cost of the permanent magnet motor while meeting the performance requirements of the permanent magnet motor.

[0016] Optionally, the thickness of the first sub-part is equal to the thickness of the second sub-part.

[0017] According to the rotor of this application, the structural setup can be simplified while ensuring air gap magnetic flux balance, thereby improving the power output smoothness and speed regulation capability of the permanent magnet motor.

[0018] According to the rotor of this application, the permanent magnet is made of ferrite magnet steel.

[0019] According to the rotor of this application, the cost of ferrite is relatively low, and when the permanent magnet is made of ferrite steel, the overall cost of the permanent magnet motor can be effectively reduced while meeting the performance requirements of the permanent magnet motor.

[0020] According to the rotor of this application, one or more magnetic blocking holes are provided between two permanent magnets belonging to the same magnetic pole; and / or, the two mounting cavities corresponding to the two permanent magnets belonging to the same magnetic pole are connected and the two permanent magnets are spaced apart.

[0021] According to the rotor of this application, the gap between the two permanent magnets is relatively large. Setting one or more magnetic blocking holes here helps to ensure the overall mechanical structural strength of the rotor core. The two mounting cavities corresponding to the two permanent magnets belonging to the same magnetic pole are connected. The air gap formed by the gap between the two permanent magnets is used for insulation, thereby simplifying the processing difficulty of the rotor core and making effective use of space.

[0022] Secondly, this application provides a permanent magnet motor, including a stator and the aforementioned rotor, with the rotor disposed within the stator.

[0023] Optionally, the number of slots in the stator is S, and the number of magnetic poles in the rotor is P, where S and P satisfy: S / P = 3 / 2.

[0024] According to the rotor of this application, when the rotor is applied to a permanent magnet motor, the permanent magnet motor has a concentrated winding structure, which can effectively reduce the amount of copper used at the ends of the rotor core, reduce the loss and cost of the permanent magnet motor, and thus improve the efficiency of the permanent magnet motor.

[0025] According to the permanent magnet motor of this application, the inner diameter and outer diameter of the stator are D1 and D2, respectively, where D1 and D2 satisfy: D1 / D2>0.6; and / or the tooth width of the stator is K1, and the width of the yoke of the stator is K2, where K1 and K2 satisfy: 1.05 <K1 / K2<1.1。

[0026] According to the permanent magnet motor of this application, setting D1 / D2>0.6 can increase the splitting ratio energy of the permanent magnet motor, thereby increasing the amount of permanent magnets used, and thus improving the air gap magnetic flux density of the permanent magnet motor to achieve the effect of improving the low frequency efficiency of the permanent magnet motor. Since the magnetic poles are V-shaped, the magnetic circuit will mostly form a loop through the teeth of the stator. The magnetic circuit density of the stator teeth is relatively high. Therefore, by reasonably optimizing the width of the stator teeth and yoke, it can be ensured that the magnetic circuit of the stator will not saturate. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0030] Figure 1 A schematic diagram of a rotor provided for some embodiments of this application;

[0031] Figure 2 A schematic diagram of a rotor provided for further embodiments of this application;

[0032] Figure 3 A schematic diagram of a permanent magnet motor provided for some embodiments of this application;

[0033] Figure 4 This is a schematic diagram of the stator of a permanent magnet motor provided for some embodiments of this application.

[0034] Explanation of reference numerals in the attached figures:

[0035] Rotor 1, rotor core 10, shaft hole 11, mounting cavity 12, magnetic blocking hole 13, magnetic pole 20, permanent magnet 21, first sub-section 211, second sub-section 212.

[0036] Stator 2, permanent magnet motor 100. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0039] For ease of description, spatial relative terms may be used in the text to describe the relative position or movement of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "front," "back," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure undergoes a positional flip, orientation change, or change of motion, these directional indications will change accordingly. For instance, an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0040] like Figure 1 As shown, the rotor 1 according to an embodiment of this application includes a rotor core 10 and a plurality of permanent magnets 21. The rotor core 10 includes a shaft hole 11, and a plurality of mounting cavities 12 are spaced apart on the outer periphery of the shaft hole 11. The permanent magnets 21 are embedded in the mounting cavities 12. Every two adjacent permanent magnets 21 with the same polarity form a group of magnetic poles 20 distributed in a V-shape, and the tips of the magnetic poles 20 face the shaft hole 11. The cross-sectional area of ​​the permanent magnet 21 in the radial direction of the rotor core is S1, the remanence of the permanent magnet 21 is Br, the outer diameter of the rotor core 10 is R, and the diameter of the shaft hole 11 is r. S1, Br, R, and r satisfy: 0.051 ≤ S1*Br / (R 2 -r 2)≤0.053.

[0041] Wherein, S1*Br / (R 2 -r 2 The ) can be 0.0515, 0.052, 0.0525 and 0.053.

[0042] According to the rotor 1 of this application embodiment, every two adjacent permanent magnets 21 with the same polarity form a V-shaped distribution of magnetic poles 20, with the tips of the magnetic poles 20 facing the shaft hole 11. When this rotor 1 is applied to a permanent magnet motor 100, the magnetic focusing effect of the magnetic poles 20 is fully utilized, which can effectively improve the air gap magnetic flux density of the permanent magnet motor 100, improve the back electromotive force waveform, and help improve the torque output performance of the permanent magnet motor 100. The larger the remanence and cross-sectional area of ​​the permanent magnet 21, the stronger the anti-demagnetization ability of the permanent magnet 21. However, if the remanence and area are too large, on the one hand, it will affect the mechanical structural strength of the rotor core 10, and on the other hand, it may increase the production cost and cause magnetic circuit saturation. Therefore, the ratio of the product of the remanence and the cross-sectional area of ​​the permanent magnet 21 to the cross-sectional area of ​​the rotor core is set to meet a certain range, so as to improve the efficiency of the permanent magnet motor 100 when operating at low frequency and avoid magnetic circuit saturation of the rotor core 10.

[0043] It is understandable that adjacent magnetic poles 20 have opposite magnetic properties. For example, rotor 1 includes four magnetic poles 20, with the N pole of the first magnetic pole 20 facing outwards, the S pole of the second magnetic pole 20 facing outwards, the N pole of the third magnetic pole 20 facing outwards, and the S pole of the fourth magnetic pole 20 facing outwards in a clockwise or counterclockwise direction.

[0044] According to the embodiment of this application, the rotor 1 has a number of magnetic poles 20 of P, where P is greater than or equal to 8, and the included angle of the magnetic poles 20 is θ, where θ satisfies: 0 < θ < 50°.

[0045] Where P can be 8, 9, 10, or 11, etc. θ can be 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45°, etc. It can be understood that within the range of 0–50°, as the included angle increases, the magnetic permeable area inside the rotor core 10 gradually increases, the magnetic reluctance of the magnetic circuit decreases, and the air gap magnetic flux density increases. Therefore, it can be set appropriately according to needs.

[0046] According to the rotor 1 of this application embodiment, more magnetic poles 20 are provided within a limited space. When the rotor 1 is applied to the permanent magnet motor 100, it helps to improve the power density of the permanent magnet motor 100. When the size of the shaft hole 11 is fixed, the width of the permanent magnet 21 is affected by the included angle of the magnetic poles 20. The smaller θ is, the larger the width of the permanent magnet 21, which in turn affects the performance parameters of the permanent magnet motor 100, such as the air gap flux density and cogging torque. Therefore, it is necessary to set an appropriate value of θ to ensure the air gap flux density of the permanent magnet 21. Thus, this setting can ensure that the permanent magnet 21 can withstand a large operating current without demagnetizing when it is working.

[0047] like Figure 1 As shown, in some embodiments, the permanent magnet 21 has a rectangular cross-sectional shape in the radial direction of the rotor core 10, with a width of Lm and a thickness of Hm, where Lm and Hm satisfy: 0.37 <Lm / (R-r)<0.4,5<Lm / Hm<6。

[0048] Wherein, Lm / (Rr) can be 0.372, 0.374, 0.376, 0.378, 0.38, 0.382, 0.384, 0.386, 0.388, 0.39, 0.392, 0.394, 0.396, and 0.398, etc. Lm / Hm can be 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, and 5.9, etc.

[0049] According to the rotor 1 of this application embodiment, the magnetic reluctance of the direct-axis magnetic circuit of the permanent magnet 21 is mainly determined by the thickness of the permanent magnet 21 in the magnetization direction, which will cause changes in the performance of the permanent magnet motor 100. Within a certain range, increasing the thickness of the permanent magnet 21 will increase the energy of the magnetic field of the permanent magnet 21, and the air gap magnetic flux density and cogging torque will also increase. At the same time, the magnetic reluctance of the direct-axis magnetic circuit will also increase. However, when it exceeds a certain range, local magnetic flux saturation will occur in the rotor core 10. Increasing the width of the permanent magnet 21 will reduce the leakage magnetic phenomenon and generate a stronger permanent magnet torque. However, when it exceeds a certain range, local magnetic flux saturation will occur in the rotor core 10. Therefore, it is necessary to reasonably set the values ​​of Lm and Hm to avoid magnetic flux saturation.

[0050] like Figure 2 As shown, according to the embodiment of this application, the permanent magnet 21 of the rotor 1 includes a first sub-part 211 and a second sub-part 212 arranged sequentially along the width direction. The first sub-part 211 is close to the shaft hole 11, and the second sub-part 212 is close to the outer circle of the rotor core 10. The coercivity of the second sub-part 212 is greater than that of the first sub-part 211.

[0051] According to the embodiment of this application, the magnetic circuit of the rotor 1 is more dense in the direction closer to the outer circle of the rotor core 10, making it easier to demagnetize. Setting the coercivity of the second sub-part 212 to be greater than that of the first sub-part 211 can improve the demagnetization resistance of the permanent magnet 21.

[0052] like Figure 2 As shown, in some embodiments, the cross-sectional shape of the first sub-part 211 and the second sub-part 212 is rectangular, and the width of the first sub-part 211 is greater than the width of the second sub-part 212.

[0053] According to the rotor 1 of this application embodiment, the material with high coercivity has a high cost. Under the premise of meeting the performance of the permanent magnet motor 100, setting the width of the first sub-part 211 to be greater than the width of the second sub-part 212 can effectively reduce the overall cost of the permanent magnet motor 100.

[0054] In some embodiments, the thickness of the first sub-part 211 is equal to the thickness of the second sub-part 212.

[0055] According to the rotor 1 of the present application embodiment, the structural configuration can be simplified while ensuring air gap magnetic flux balance, thereby improving the power output smoothness and speed regulation capability of the permanent magnet motor 100.

[0056] According to the embodiments of this application, the rotor 1 and the permanent magnet 21 are made of ferrite magnets.

[0057] According to the rotor 1 of the present application embodiment, the cost of ferrite is relatively low. When the permanent magnet 21 is made of ferrite magnet, the overall cost of the permanent magnet motor 100 can be effectively reduced while meeting the performance requirements of the permanent magnet motor 100.

[0058] According to the embodiments of this application, the rotor 1 has one or more magnetic blocking holes 13 between two permanent magnets 21 belonging to the same magnetic pole 20.

[0059] According to the embodiment of this application, the rotor 1 has a large space between the two permanent magnets 21 belonging to the same magnetic pole 20 and has a magnetic circuit, which is suitable for setting the magnetic blocking hole 13 here, which helps to ensure the overall mechanical structural strength of the rotor core 10.

[0060] According to the embodiment of this application, the rotor 1 has two mounting cavities 12 corresponding to two permanent magnets 21 belonging to the same magnetic pole 20 connected.

[0061] According to the embodiment of this application, the rotor 1 uses the gap between two permanent magnets 21 to form an air gap for insulation, thereby simplifying the processing difficulty of the rotor core 10 and making effective use of space.

[0062] like Figure 3 and Figure 4As shown, the permanent magnet motor 100 according to an embodiment of the present application includes a stator 2 and the above-mentioned rotor 1, and the rotor 1 is disposed inside the stator 2.

[0063] In some embodiments, the number of slots of the stator 2 is S, and the number of magnetic poles 20 of the rotor 1 is P, and S and P satisfy: S / P = 3 / 2.

[0064] According to the rotor 1 of an embodiment of the present application, through such a constraint, when the rotor 1 is applied to the permanent magnet motor 100, the permanent magnet motor 100 is a concentrated winding structure, which can effectively reduce the amount of copper used at the end of the rotor core 10, reduce the loss and cost of the permanent magnet motor 100, and thus improve the efficiency of the permanent magnet motor 100.

[0065] As Figure 4 shown, for the permanent magnet motor 100 according to the present application, the inner diameter and outer diameter of the stator 2 are D1 and D2 respectively, and D1 and D2 satisfy: D1 / D2 > 0.6. Among them, D1 / D2 can be 0.65, 0.7, 0.75, 0.8, etc.

[0066] For the permanent magnet motor 100 according to an embodiment of the present application, setting D1 / D2 > 0.6 can increase the splitting ratio energy of the permanent magnet motor 100, thereby increasing the amount of permanent magnet 21 used, and further improving the air-gap magnetic flux density of the permanent magnet motor 100 to achieve the effect of improving the low-frequency efficiency of the permanent magnet motor 100.

[0067] For the permanent magnet motor 100 according to an embodiment of the present application, the tooth width of the stator 2 is K1, and the width of the yoke part of the stator 2 is K2, and K1 and K2 satisfy: 1.05 < K1 / K2 < 1.1. Among them, K1 / K2 can be 1.055, 1.06, 1.065, 1.07, 1.075, 1.08, 1.085, 1.09, 1.095, etc.

[0068] For the permanent magnet motor 100 according to the present application, since the magnetic poles 20 are in a V shape, most of the magnetic circuits will form a loop through the tooth part of the stator 2, and the magnetic circuit density of the tooth part of the stator 2 is relatively high. Therefore, by reasonably optimizing the widths of the tooth part and the yoke part of the stator 2, it can be ensured that the magnetic circuit of the stator 2 will not be saturated.

[0069] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0070] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0071] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A rotor, characterized in that, The rotor core includes a rotor core and multiple permanent magnets. The rotor core includes a shaft hole with multiple mounting cavities spaced apart on its outer periphery. The permanent magnets are embedded in these mounting cavities. Each pair of adjacent permanent magnets with the same polarity forms a V-shaped magnetic pole with the tips of the poles facing the shaft hole. The cross-sectional area of ​​the permanent magnet in the radial direction of the rotor core is S1, the remanence of the permanent magnet is Br, the outer diameter of the rotor core is R, and the diameter of the shaft hole is r. S1, Br, R, and r satisfy: 0.051 ≤ S1 * Br / (R 2 -r 2 )≤0.

053.

2. The rotor according to claim 1, characterized in that, The number of magnetic poles is P, where P is greater than or equal to 8, and the angle between the magnetic poles is θ, where θ satisfies: 0 < θ < 50°.

3. The rotor according to claim 2, characterized in that, The permanent magnet has a rectangular cross-sectional shape in the radial direction of the rotor core. The width of the permanent magnet is Lm, and the thickness is Hm, where Lm and Hm satisfy: 0.37 <Lm / (R-r)<0.4,5<Lm / Hm<6。 4. The rotor according to claim 1, characterized in that, The permanent magnet includes a first sub-section and a second sub-section arranged sequentially along the width direction. The first sub-section is close to the shaft hole, and the second sub-section is close to the outer circle of the rotor core. The coercivity of the second sub-section is greater than that of the first sub-section.

5. The rotor according to claim 4, characterized in that, Both the first sub-part and the second sub-part have rectangular cross-sectional shapes, and the width of the first sub-part is greater than the width of the second sub-part.

6. The rotor according to claim 5, characterized in that, The thickness of the first sub-part is equal to the thickness of the second sub-part.

7. The rotor according to any one of claims 1-3, characterized in that, The permanent magnet is made of ferrite magnet steel.

8. The rotor according to any one of claims 1-6, characterized in that, One or more magnetic blocking holes are provided between two permanent magnets belonging to the same magnetic pole; and / or, the two mounting cavities corresponding to the two permanent magnets belonging to the same magnetic pole are connected and the two permanent magnets are spaced apart.

9. A permanent magnet motor, characterized in that, It includes a stator and a rotor as described in any one of claims 1-8, wherein the rotor is disposed within the stator.

10. The permanent magnet motor according to claim 9, characterized in that, The stator has S slots and the rotor has P poles. S and P satisfy: S / P = 3 / 2.

11. The permanent magnet motor according to claim 9, characterized in that, The inner and outer diameters of the stator are D1 and D2, respectively, where D1 / D2 > 0.6; and / or the tooth width of the stator is K1, and the width of the yoke of the stator is K2, where K1 and K2 satisfy 1.

05. <K1 / K2<1.1。

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